I just look your codepen. After few tests, I saw two containers with class video-slider with a video tag with the same id "video" inside. (Check with debug console on the render view and the jquery code $(".video-slide").children()).

You can start the videoS with the jquery code $(".video-slide").children().each(function() { this.play(); }); but before you need to find where and why your blocks are duplicated.